Solar power has the potential to provide a significant portion of humanity's energy requirements. It is estimated that the Earth's land and oceans receive solar radiation at a rate of 96 petawatts (PW), or over 5,000 times the current rate of energy consumption worldwide. Harnessing solar power is problematic, however, because the absolute power level per unit area is relatively low. In the southwest region of the United States, for example, where solar energy is relatively plentiful, insolation averages approximately 5.5 kWh/m2 per day. A number of approaches have been developed to transform solar energy into other forms of energy. For example, concentrating solar power (CSP) systems utilize lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated light is then used as a heat source for a conventional power plant. Photovoltaic systems including solar panel arrays coupled to batteries and an inverter are also known.
Although installation of solar power systems for specialized applications is growing rapidly, solar power accounts for less than one-half percent of total energy consumption worldwide. A large percentage of this growth to date has been stimulated by government subsidies. In order for solar power to emerge as a primary energy source that is competitive with other forms of energy, a reduction in the installation cost per watt is necessary. Because harvesting solar power does not consume fuel resources, the cost of solar power is relatively low after installation is complete. The current cost per installed watt is approximately $5-7 USD for moderate to large scale installations.